Herein, related art may be discussed to put the invention in context. Related art labeled “prior art” is admitted prior art; related art not labeled “prior art” is not admitted prior art.
Computer systems typically store boot firmware in non-volatile memory, such as read-only memory (ROM) or flash memory, that is addressed by default when a computer is turned on. This boot firmware contains initialization routines and points to locations whence an operating system can be launched to a user-friendly state.
A multiprocessor boot procedure involves copying a boot “image” from relatively slow non-volatile boot memory to relatively fast rewritable, random-access memory (RAM). In a typical multiprocessor system, the boot process has two phases. In the first phase, each processor must access the boot memory in turn to establish its state to cooperate with the other processors and to select a “monarch” processor. In the second phase, the monarch copies the boot image into RAM while the other processors, “serfs”, sleep. After preparing the RAM for multi-processor use, the monarch awakens each serf and the multiprocessor computer system runs from RAM. Thus, each processor in a multiprocessor computer boots using identical boot firmware.
When a “crash”, a specific class of system error, occurs, the boot image in RAM is sometimes corrupted and therefore cannot be trusted. Accordingly, in response to a crash, all processors recopy boot images from non-volatile boot memory to ensure their error handling and recovery instructions are from identical and trusted boot images.
Booting and error handling, or any boot ROM access, especially in a multiprocessor system, is quite time consuming. The present invention addresses the problem of reducing the time for a multiprocessor system to finish all processor accesses to an identical boot ROM image. Other problems addressed by the invention are apparent from the description below.